Electrostatic instrument.



No. 731,787. I PATENTED JUNE 23, 1903.

E. J. KING.

ELECTROSTATIC INSTRUMENT.

APPLICATION FILED MAR. 27. 1901.

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PATENT ED JUNE 23, 1903.

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25 ground from the needle.

Patented June 23, 1903. I

UNITED STATES P TENT OFFIcE.

ELTON J. KING, OF FORT WAYNE, INDIANA, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ELECTROSTATIC INSTRUMENT.

SPECIFICATION forming part of Letters Patent No. 731,787, dated June 23, 1903. Application filed March 27, 1901. Serial No. 53,042. (No model.)

To all whom it may concern.-

Be it known that I, ELTON J. KING, a citi zen of the United States, residing at Fort Wayne, county of Allen, State of Indiana, have invented certain new and useful Improvements in Electrostatic Instruments, of

which the following is a specification. The object of this invention is to provide an electrostatic indicating instrument of im- 16 proved construction in point of simplicity,

cheapness, and reliability of action.

ground-detectors in which an indication is given as to the side of acircuit on which a v I 5 ground occurs,though the invention is also applieable to electrostatic instruments of other character, such as voltmeters. In devices of this character as commonly constructed a needle or pointer is connected with a pair 20 of metal vanes, which are mounted on jeweled bearings in an electrostatic field formed of conducting surfaces or plates connecting with the two sides of an electric-circuit, an

inductive or electric path being provided to In the normal condition of such an instrument, so long. as both sides of the line are insulated, the needle being equally influenced by both the electrostatic surfaces remains unaifectedflout if a ground occurs onone side of theiline a decreased electrostatic charge on vthat side causes a deflection of the needle. In '-most devices of this character the movable vanes to which the needle or pointer is attached are I electrically connected with the ground. Im-

portant improvements involve a form of electrostatic surface or vane which yields a betterresult, in that I provide the edge of the vanes with points or projections which admit 40 of a better action, and thereby increase the efiectiveness of operation, and instead of connecting the movable vanes directly to ground I interposean insulating-gap between two conducting-surfaces providedalso with points. or protuberances, one of these being couneeted to ground and the other to the movable vanes.

The several features of novelty of my invention will be more particularly hereinafter vanes. My invention is particularly applicable to described, and will be definitely indicated in the claims appended to this specification.

In the accompanying drawings, which illustrate my invention as applied to a grounddetector, Figure 1 is a front elevation. Fig.

2 is a side view, partially in section. Fig. 3 is a diagram showing the operative relation of an instrument embodying my improvements to an electric circuit, and Figs. 4 and 4c detached views of my improved form of 1 and 1 represent two metallic surfaces connected by stout metal conductors with two terminals 2 2 mounted on the back of the instrument and adapted for connection with two sides of an electric circuit. These electrostatic surfaces are formed of punchings of thin sheet metal having a pointer or serrated edge, as indicated in Fig. 4, and are curved, as indicated in Fig. 1, to provide a uniform width of air-gap for cooperating vanes 3 3, carried by a frame pivotedat a point midway between the surfaces 1 1, but in a line laterally displaced from the line connecting the centers of area of the surfaces 1 1. The vanes 3 3 are similarly formed of apunching or stamping of sheet metal having serrated edges, as indicated in Fig. 4:, and fastened by screws or pins to an arbor or shaft supported in jeweled bearings in a bracket 4 of sheet metal. As seen in Figs. 1 and 2, eon- 8o necting the metal bracket with the needle and thevanes 3 and 3, to which the latter is electrically connected, is a ductile spiral conductor 5 with as small a degree of elasticity as practicable. The bracket 4 is electrically connected with a metallic surface 6, the lower part of which is serrated and cooperates with similarly-serrated surfaces 7 7 having an electrical connection with ground through a post 8. A scale-plate 9 is mounted incoopero ative relation with the point of the needle and may be calibrated, as indicated in Fig. 1, to indicate the degree of deflection. An instrument thus constructed may be connected with an electric circuit, as indicated "in Fig. 5 3, or in any other manner-that is to say, in series or in parallel. Under normal conditions, when the two sides of the circuit to which the instrument is connected are well insulated, equal and opposing torques are exerted on both sides of the needle and it remains in its zero position. If, however, a leak occurs on one side, the decrease of potential on the electrostatic surface corresponding to that side permits the torque ofthe opposite side to prevail, thereby deflecting the needle toward the side on which the ground occurs. I find that this action is greatly improved by the equipment of the electrostatic surfaces with the points already described. I'do not commit myself to any theory as to the cause of the improved action. I'believe, however, that the described arrangement of the opposing vanes effects an increased electrostatic stress and greater density in lines between adjacent edges, and this seems to produce a better result than when the charge is more uniformly distributed. Iarrange the confronting surfaces so that the points are staggered-that is to say, the points of one surface confront the depressions of an- I prising two conducting-surfaces adapted for other, as indicated in Fig. 2, the points 3 of the movable element confronting the recess 1 of the fixed surface, though the instrument is operative if the points of one surface correspond to those of the opposing surfaces. It is, moreover, not essential that the vanes 3 3 should swing concentrically with the curvature of the surfaces 1 1, since the tendency is to shift the movable surfaces into a position of minimum dielectric resistance.

The insertion of the auxiliary gap between the electrostatic surfaces 6, 7 and 7 enables me to obtain a better result than could be obtained by providing the movable element with a direct ground and permits even the employment of a similar plan in the construction of an electrostatic voltmeter, the arrangement of which will be evident to those familiar with the art.

What I claim as new, and desire to secure by Letters Patent of the United States, is 1. An electrostatic indicator, comprising conducting-surfaces with leads for different sides of a circuit, and an indicator movable relatively to the surfaces in a plane, the cooperating surfaces being armed with points.

' 2. An electrostatic instrument comprising metallic surfaces having leads for different sides of acircuit, and metallic surfaces movable relatively thereto, the conducting-surfaces of one set having a serrated edge with tapering teeth.

3. An electrostatic indicator, comprising conducting-surfaces provided with leads for different sides of a circuit, and a movable indicator carrying cooperating vanes, one set of the cooperating conducting-surfaces tapering in the direction of movement, the centers of area of which are laterally displaced in the ating therewith having their centers of area displaced relatively to those of the cooperating surfaces, and a plurality ofp'oints to concentrate the charge at determinate parts.

5. An electrostatic instrument, comprising conducting-surfaces provided with leads for difierent sides of a circuit, a movable indicator provided with vanes, the confronting surfaces across both gaps being armed with tapering conducting-teeth.

6. An electrostatic instrument, comprising conducting-surfaces adapted to be connected with different sides of a circuit, a movable indicator, provided with vanes cooperating with said surfaces, and an insulating-gap between the indicator and the ground.

7. An electrostatic ground-detector, comconnection with different sides of a circuit, a movable indicator provided with vanes confronting the respective surfaces, and an insulating-gap between the indicator and the a ground, said gap being walled with conducting-points.

8. An electrostatic ground-detector, comprising two conducting-surfaces serrated on one edge and adapted for connection with the two sides of a circuit, a movable indicator carrying vanes cooperating with said surfaces, and a ductile spiral conductor connecting the vanes with a fixed ground-plate.

9. An electrostatic instrument comprising two conducting-surfaces provided with leads for different sides of a circuit, and a movable indicator carrying cooperating vanes, the opposing surfaces being armed with points in staggered relation across the gap.

10. In an electrostatic measuring instrument,an electrostatic surface acting on the indieator having an indented or irregular edge.

11. In the ground of an electrostatic grounddetector, a gap of suflicient width to normally insulate, but sufficiently narrow to permit of static induction.

12. In an electrostatic instrument, an indicator, electrostatic surfaces in cooperative relation thereto, and two opposed surfaces in the path of discharge separated by a dielectric.

In witness whereof I have hereunto set my hand this 22d day of March, 1901.

ELTON J. KING.

IFO 

